Gatling can be configured and optimized in three ways:

  • with configuration files, located in conf directory
  • with command line options
  • with $JAVA_OPTS environment variable

Configuration files


This file allows you to configure the log level of Gatling. For further information, you should have a look at Logback Documentation.


In order to log requests and responses, uncomment the dedicated loggers in the default logging configuration file.


Gatling configuration is based on the great Typesafe Config library.

Gatling configuration files, such as the default configuration file uses the HOCON format.

Gatling uses a fallback strategy, where:

System properties > gatling.conf > gatling-defaults.conf

gatling.conf is placed in the conf directory. It serves as an easy-to-edit base: all properties are commented and all values are the defaults.

gatling-defaults.conf is shipped in the gatling-core jar and should not be edited.

If you want to override default values, you have two possibilities:

  • change the value in gatling.conf.
  • set a System property (the name of the property must match HOCON Path)


When editing gatling.conf, don’t forget to remove the leading # that comments the line, otherwise your change will be ineffective.

Command Line Options

Gatling can be started with several options listed below:

Option (short) Option (long) Description
-h -help Help
-nr –no-reports Runs simulation but does not generate reports
-ro <folderName> –reports-only <folderName> Generates the reports for the simulation log file located in <gatling_home>/results/<folderName>
-df <path> –data-folder <path> Uses <path> as the folder where feeders are stored
-rf <path> –results-folder <path> Uses <path> as the folder where results are stored
-bdf <path> –bodies-folder <path> Uses <path> as the folder where bodies are stored
-sf <path> –simulations-folder <path> Uses <path> as the folder where simulations are stored
-bf <path> –binaries-folder <path> Uses <path> as the folder where simulation binaries are stored
-s <className> –simulation <className> Uses <className> as the name of the simulation to be run
-on <name> –output-name <name> Uses <name> for the base name of the output directory
-rd <description> –run-description <description> A short <description> of the run to include in the report
-m –mute Runs in mute mode: doesn’t ask for run description or simulation ID, uses defaults


Default command line options for JAVA are set in the launch scripts. You can use the JAVA_OPTS var to override those defaults, eg:

~$ JAVA_OPTS="myAdditionalOption" bin/